An elevator used in a general building includes a winding machine installed on the building, a cage for carrying people, and a wire rope connecting the winding machine and the cage so that the cage is lifted or lowered by winding or unwinding the wire rope.
Such an elevator is provided with a braking apparatus, which is used when the cage needs emergency braking in an emergency.
The braking apparatus is installed on the cage and is configured to grasp the main rope, when emergency braking is needed, to prevent the cage from moving.
There have been extensive research and development on such rope braking apparatuses in line with stricter regulations for preventing accidents related to elevators, but most of such braking apparatuses, which usually employ a combination of hydraulic or pneumatic pressure and elastic force from springs, have problems in that the braking force may be degraded by leakage of the fluid, when hydraulic pressure is used, requiring frequent checkup of the hydraulic or pneumatic pressure.
Braking apparatuses have recently been proposed, which do not employ any hydraulic or pneumatic structure, but solely use elastic force from springs.
Examples of such braking apparatuses include Korean Patent Registration No. 0609836, entitled “Rope Braking Device for Elevator” and Korean Utility Model Laid-Open No. 2008-3368, entitled “Rope Locking Device of the Rope Brake for Elevator”.
Such conventional apparatuses share the following operation scheme: a separate operation panel is connected to a rope pressurization plate and a compression spring via a link mechanism, and expansion of the spring causes rotation the operation panel and then movement of the pressurization plate, which pressurizes the rope.
Although the problem of fluid leakage can be solved, the following problem still exists.
When the pressurization plate is configured to pressurize the rope as a result of rotation of the operation panel as described above, the pressurization plate does not move along a straight line, but pivots along the trajectory of rotation of the operation panel to apply pressure. Therefore, the direction of pressure applied by the pressurization plate is not perpendicular but oblique to the rope.
As a result, there is a difference between a pressure applied to the upper portion of the rope and a pressure applied to its lower portion, making the braking force unstable, and there is also a possibility that friction force will be concentrated at a specific location on the rope, which may cause uneven wear of the rope or even cause the rope to break up.